I'm thinking I need to re-wire the stereo system on our boat. As it is, there are 3 amps: 1 for the original speakers, 1 for the sub, and 1 for the tower speakers. All 3 amps are wired to the stereo outputs. Everything works, BUT... I only have 1 control for the volume. I can't turn the tunes up loud enough for the rider to hear, without blaring the boat speakers and sub.

So, how did you wire your system?

It was suggested that I use a equalizer like this one: Clarion EQS746. With it I can independently control the sub and volume levels, as well as fade to the tower speakers. That seems like the cheapest fix, but is that the best way to go?